Fuel economy at 65 mph vs 60 mph

We don't really care about fuel mileage anymore. I look at it this way. We just spent 21 days and 2200 miles on the road having fun, Fuel + RV parks came out to $78.00 a day over the whole trip. Out west here you cant even stay in a decent hotel for $78.00 a night and you would still have fuel cost. When ever anyone says wow what mileage do you get pulling that fifth wheel. I just ask them can you do the same things I do cheaper than $78.00 bucks a day????? My thought is if I need to get a certain mileage 12mpg not 9mpg It is time to stop traveling and just stay home, like most the people that ask me wow what mpg do you get pulling that fifth wheel. I understand people have a budget and this way of thinking is not for all, But it cost to travel so you pay gas or you pay hotels.